1. Field of the Invention
The present invention relates to graphical images and, more particularly, to format conversion of graphical images.
2. Description of the Related Art
Graphic images are often stored as image files in a variety of different formats. Often these formats contain some sort of compression to keep the size of the image files manageable. For example, GIF, TIFF and JPEG are popular formats for image files.
However, with conversion between image formats sometimes features supported in one format are not supported in the other format. Such discrepancies lead to incomplete conversion of the images such that the resulting images when displayed are not identical and sometimes have distinct differences. For example, GIF89a supports transparency, but JPEG does not. Hence, conversion of GIF89a images presents a problem because JPEG does not support transparency data. For example, straightforward conversion of GIF89a images to JPEG images often results in an undesirable color appearing in the resulting JPEG image. This is due to the use of an unusual color in the GIF89a image as the transparency color. With GIF89a images, the transparency color is never seen because it is treated as "transparent" when displayed. JPEG images, however, have no transparency support, so the conversion to JPEG results in a color (usually an unusual color) undesirably appearing when the JPEG image is viewed.
Thus, there is a need for improved techniques for image format conversion between formats having different transparency support.